Method of deforming a workpiece



Nov. 6, 1962 J. w. TOMKA METHOD OF DEFORMING A WORKPIECE 4 Sheets-Sheet 1 Original Filed Aug. 26, 1958 III 1962 J. w. TOMKA 3,062,423

METHOD OF DEF'ORMING A WORKPIECE Original Filed Aug. 26, 1958 4 Sheets-Sheet 2 UN IIIHII IN V EN TOR.

NOV. 6, 1962 J, w, TOMKA 3,062,423

METHOD OF DEFORMING A WORKPIECE Original Filed Aug. 26, 1958 4 Sheets-Sheet 3 INVENTOR.

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Nov. 6, 1962 J. w. TOMKA METHOD OF DEF'ORMING A WORKPIECE Original Filed Aug. 2a, 1958 4 Sheets-Sheet 4 United States Patent Ofifice 3,062,423 Patented Nov. 6, 1962 3,062,423 METHOD OF DEFQRMING A WORKPIECE Joseph W. Tomlra, Cincinnati, Ohio, assignor, by mesne assignments, to Nordberg Manufacturing Company, a

corporation of Wisconsin Original application Aug. 26, 1958, Ser. No. 757,353. Di-

vided and this application Apr. 4, 1960, Ser. No. 25,816 7 Claims. ((31. 225-1) This invention relates to a device for removing frangible rings from a bar and particularly to a device for removing cast iron thimbles from anode bars utilized in the refining of aluminum.

This application is a division of my copending application Serial No. 757,353, filed August 26, 1958.

The method most commonly utilized to produce commercially pure aluminum is to place a charge of refined ore called alumina in a carbon pot. A carbon block preferably comprising petroleum coke, pitch, and anthracite blended together and formed under pressure is lowered into the pot. An electrical current is passed through the block, which acts as the anode, and the pot, which acts as the cathode, whereupon the aluminum is melted out of the alumina ore and siphoned off. During the refining process, the carbon block burns down and must be replaced on the support bar on which it is carried.

The support bars are transported through the various operating stations by a conventional overhead conveyor system. The preformed carbon blocks are provided with a cored cavity arranged to receive a steel stub carried by the copper support bars. The block is bonded to the steel stub by pouring molten iron into the cavity surrounding the stub whereupon the iron hardens and firmly anchors the block to the stub. After the carbon block has been burned down, it is necessary that the small remaining portion of the block and the cast iron thimble, which anchored the block to the stub, be removed from the bar. In the past, the removal of the cast iron thimble has been done almost completely manually and the job was difiicult, time consuming, and costly.

It is, therefore, a primary object of the present invention to provide a device for stripping such an iron thimble from the support bar stub in a fast, etficient, and inexpensive manner.

A further object of the invention is to provide an arrangement for removing such cast iron thimbles from the steel stubs of a support bar, without removing the bar from its overhead conveyor, by press means for forcing the stub and block against wedge type strippers which act to fracture the thimble and thereby cause its effective removal from the bar stub.

The invention is best illustrated with reference to the accompanying drawings wherein:

FIGURE 1 is a front elevational view, partly in section, of the preferred embodiment of the thimble removing press;

FIGURE 2 is a side elevational view, partially in section, of the structure of FIGURE 1;

FIGURE 3 is a top plan view of the structure of FIGURE 1;

FIGURE 4 is a fragmentary vertical sectional view of the stripper punch arrangement;

FIGURE 5 is a fragmentary side view of the stripper punch and,

FIGURE 6 is a schematic valve and piping layout for the arrangement.

Referring to the drawings and particularly to FIGURES 1 and 2, it is seen that a support bar, indicated generally at 10, is carried by a conventional overhead conveyor arrangement 12. The conveyor is formed of an I-beam 14 arranged to support an anode bar body 16 through rollers 18. The moving force is supplied to the foregoing assembly by means of a drive conveyor, generally indicated at 20, which similarly is formed of an I-beam 22 arranged to support a plurality of spaced members 24 by means of rollers 26. The spaced members 24 are secured to and driven by a chain (not shown) and drives the anode bar 16 through a drive rod 28 which is secured to the support bar 10.

In the preferred form, each anode bar 16 is arranged to support a pair of carbon blocks. Obviously, however, each anode bar could be utilized to support a single carbon block. Referring to FIGURE 2, it is seen that a cross bar 39 is secured to the bar 16. The ends of the cross bar 30 are turned down as at 31 and a steel stub 32 is bonded to each of the turned down portions. A schematic cast iron thimble is indicated at 36 in FIGURES 1 and 2 and the contour of the thimble, best seen in FIGURES 4 and 5, corresponds to the contour of the cored opening in the carbon block. The stub, anode bar, support bar and overhead conveyor arrangement may be considered collectively as a carrier for the thimble. The fragmentary burned down carbon block 41 is illustrated in only certain of the views because the primary concern of the invention is the removal of the cast iron thimble from the stub, and the carbon block fragment is removed simultaneously with the thimble.

The present invention contemplates the use of a press for removing the cast iron thimbles and is best illustrated in FIGURES 1 through 3. The press, indicated generally at 38, comprises a base 40 on which are mounted spaced housings 42, the assembly being held together by means of conventional tie bolts 4-3. Each anode bar is conveyed to the press station in a manner which will be explained hereinafter. After arriving at the press stations, the anode bar is held in position and prevented from rotating by means of an ensnaring bar 44 (FIGURE 3) which is supported for horizontal movement in spaced guides 46. The ensnaring bar 44 is secured to the piston rod 48 of an air cylinder 50 which, when activated, moves the ensnaring bar 44 to a position whereat the body 16 of the anode bar is received in the U-shaped opening 5.1.

After the bar has been properly positioned, opposed stripper jaws 52 are moved into position by means of stripper jaw cylinders 54 so that the semi cylindrical openings 56 surround, but do not contact the steel stubs 32. As seen in FIGURE 1, the stripper jaws 52 move into position adjacent the upper surface of each thimble in order to restrain the thimble from upward movement during its removal from the steel stub.

The base 40 of the press 38 is provided with an hydraulic cylinder 60 which carries a ram 62 to the end of which is secured one or more stripper punches 64. The stripper punch is best illustrated in FIGURES 4 and 5. The punch at its extreme end 66 has a diameter which is less than the internal diameter of the cast iron thimble and diverges outwardly therefrom to form wedge surfaces 68. The wedge surfaces 68 may be provided at circumferentially spaced points on the punch, but preferably are formed as a single frusto-conical surface around the punch, and are formed so that their widest dimension exceeds the internal diameter of the cast iron thimble. The punch may also be provided with breaker points 70, preferably in the form of a single rod extending through the punch and extending outwardly of the wedge surfaces, as best seen in FIGURE 4. The breaker points 7i are provided with knife edges 72 for a purpose to be described hereinafter.

Referring specifically to FIGURE 4, it is seen that as the punch 64 moves upwardly, the punch end 66 contacts the lower surface of the steel stub 32 and moves the stub upwardly out of the cast iron thimble which is restrained from movement by the stripper jaws 52. As the punch continues its upward movement, the wedge surfaces 68 thereof contact the juncture of the lower surface of the thimble and the inner periphery thereof and by wedging action tend to expand the thimble. The thimble, however, being frangible, shatters and drops away from the steel stub 32. The advantages of this type of removal are that a shorter press stroke may be utilized than would be required if the stub were forced completely out of the thimble and, furthermore, the cast iron thimble immediately drops completely away from the stub and the punch rather than being received around the punch which would be the case if the thimble were not broken. In the latter instance, a separate operation would be necessary to remove the thimble from around the punch.

The shattered thimble is preferably dropped into one or more chutes (not shown) down which it slides into scrap boxes. It is, therefore, desirable to force the thimble to break in a preferred manner so that the thimble pieces will fall according to a predetermined pattern. This is accomplished by means of the breaker points 70. Referring to FIGURE 4, it is seen that, as the punch moves upwardly, the knife edges 72 are arranged to contact the bottom surface of the cast iron thimble at approximately the same time that the thimble is contacted by the wedge surfaces. The knife edges 72, therefore, exert a pressure on the thimble which causes the thimble to shatter in an axial plane substantially aligned with the breaker points. The discharge chutes can, therefore, be arranged in the most convenient position with assurance that the pieces of the broken thimble will always fall into the chutes rather than into some other parts of the press. As explained heretofore, the thimble is held stationary during a stripping operating while the punch forces the steel stub, and with it the entire support bar 10, in an upward direction. To accommodate this movement, the fixed conveyor 12 is provided with a movable portion or rail segment 82 (FIGURE 2) which is free to move upwardly with the support bar.

A counter-balance, shown generally at 80, is also provided to offset most of the weight of the conveyor portion 82 and of the support bar assembly so that its entire weight need not be carried by the punch and the punch actuating ram. The counter-balance arrangement is best shown in FIGURE 2. It comprises a frame portion 84, rigidly secured to the fixed conveyor rail 14. A counterbalance cylinder 86 is carried by the frame and is provided with a cylinder rod 83 which in turn supports a guide assembly 88 arranged to ride in tracks 90 provided on the frame 84. The movable conveyor portion is in turn supported by the guide assembly. During a stripping operation the cylinder 86 is actuated and is adjusted to provide an upward force which is just slightly less than the combined weight of the guide assembly, movable conveyor portion and support bar assembly. Thus, the stripper cylinder 60 need furnish only enough force to strip the thimble from the steel stub and can thus be made smaller than if it were required to support all of the structure above the stub.

The cycle of operation will be best understood with reference to the schematic diagram illustrated in FIG- URE 6. When the support bar carrying one or more thimbles to be removed is fed into the press station, a limit switch (not shown) is tripped to energize a control relay (not shown). Energization of the relay energizes a solenoid 100 whereby the spool of valve 102 is shifted to accommodate flow of shop air from port Q of valve 102 to port S and thence to the head end of air cylinder 86 whereby a counterbalancing force is provided as explained heretofore. Simultaneously with the energization of solenoid 100, solenoid 110 is energized to shift the spindle of valve 112 to supply air to the head end of ensnaring cylinder 50 which moves the ensnaring bar (FIGURE 3) into position to prevent further motion of the support bar 10. When the ensnaring bar has reached its extreme position, limit switch 114 is tripped to complete a circuit to energize solenoid 116 of pressure compensating pump 118. Oil is now pumped through line 119 to the head ends of the four stripper jaw cylinders 54 which move the stripper jaws into position immediately adjacent the upper surfaces of the related thimbles and surrounding, but not contacting, the related steel stubs. Each of the stripper jaws, when reaching its proper position, trips an associated limit switch. These switches are designated 120, 122, 124, and 126. When all four limit switches have been tripped, a relay (not shown) is energized to complete a circuit to solenoid 132 of pressure compensating pump 134 whereby oil flows through line 135 into the head end of the stripper cylinder 60. The ram 62, together with the punch 64, now moves upwardly as described heretofore to perform the stripping operation.

In certain instances sufilcient tonnage may not be attained by the ram 62 to strip a thimble from the stub. To alleviate this situation, a pressure switch 136 is provided which is set at the maximum pressure of the pump 134 and which will trip when this pressure is reached in order to allow the ram 62 to return to its lowered position and, therefore, not stop the press cycle. In these instances, of course, the thimbles have to be removed by hand.

After the ram 62 has completed its stripping operation, it travels until limit switch 138 is tripped causing solenoid 116 to be de-energized and solenoid 140 to be energized. Oil now flows through line 142 into the rod ends of the four stripper jaw cylinders 54 and the stripper jaws are consequently moved away from the support bar assembly. Simultaneously, solenoid 132 of pump 134 is de-energized and solenoid 148 is energized. Oil now flows through line 150 and check valve 151 to the rod end of the cylinder 68 whereupon the ram 62 moves downwardly. At the same time, a pilot line 152 supplies oil pressure to the spindle of bypass valve 154 to shift the valve to open position. Part of the oil, therefore, from the head end of cylinder 60, is forced out of the cylinder through line 150 and back to the reservoir 156 while the excess oil travels through by-pass valve 154 to the reservoir 156. When the ram 62 reaches its lowest position, limit switch 160 is tripped to de-energize solenoid 148 of pump 134 to neutralize the pressure in the lines leading from this pump.

When all four of the stripper jaw rams have completed their return stroke, pressure builds up at the rod end of the cylinders 54 until the pressure setting of switch 162 is reached. The switch 162 is thereby tripped and a circuit is completed to de-energize solenoid 140 of pump 118 to neutralize the pressure in this pump. Simultaneously, solenoids 100 and 110 are de-energized. De-energizing solenoid 100 reverses the ram of cylinder 86 to relieve the pressure in the counterbalance arrangement. De-energizing solenoid 110= reverses the ram of cylinder 50 whereupon the ensnaring bar 48 is moved to its retracted position. At this time, a limit switch 166 is tripped indicating the end of the cycle whereupon the conveyor mechanism 2t) feeds the support bar out of the press and moves another support bar into the press to cause the cycle to be repeated.

I claim:

1. In a method of removing a generally tubular frangible thimble from a carrier received therein, the steps of: moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding the thimble against upward movement and against rotational movement; then exerting an upward force against said carrier while counterbalancing a major portion of the weight of the carrier and the movable rail; and then directing, simultaneously, an upward wedge action against the juncture of the inner periphery and the bottom surface of said thimble, and an upward force against spaced points on the bottom surface of said thimble.

2. In a method of removing a frangible thimble from a carrier received therein, the steps of moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding the thimble against upward movement and against rotational movement; then exerting an upwardly directed force against said carrier; and then directing simultaneously, an upward wedging action against a portion of the inner periphery of the thimble and an upward force against at least two spaced points on the bottom surface of the thimble until the thimble is broken.

3. In a method of removing a frangible thimble from a carrier received therein, the steps of: moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding the thimble against upward movement; then exerting an upward force against said carrier; and then simultaneously directing an upward wedging action against the inner periphery of the thimble and an upward force against at least two spaced points on the bottom surface of the thimble.

4. In a method of removing a frangible thimble from a carrier received therein, the steps of: moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding the thimble against upward movement; then exerting an upward force against said carrier while counterbalancing a major portion of the weight of the carrier and the movable rail; and then simultaneously directing an upward wedging action against the inner periphery of the thimble and an upward force against at least two spaced points on the bottom surface of the thimble.

5. In a method of removing a frangible thimble from a carrier received therein, the steps of: moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding a portion of the thimble against upward movement; then forcing said carrier in an upward direction relative to said thimble while counterbalancing a major portion of the weight of the carrier and the movable rail; and then directing an upward wedging action against said thimble.

6. In a method of removing a frangible thimble from a carrier received therein, the steps of: moving the carrier from a fixed rail to an upwardly movable rail while such movable rail is in alignment with the fixed rail; then holding a portion of the thimble against upward movement; then forcing said carrier in an upward direction relative to said thimble; and then directing an upward wedging action against said thimble.

7. In a method of deforming a workpiece carried by an overhead carrier, the steps of moving the carrier received by the workpiece from a fixed rail segment to an upwardly movable rail segment aligned with said fixed rail seg ment, then restraining a portion of the workpiece from upward movement, and then directing an upwardly working force on another portion of the workpiece while counterbalancing a major portion of the weight of said movable rail segment, carrier and workpiece.

References Cited in the file of this patent UNITED STATES PATENTS 1,622,029 Dovel Mar. 22, 1927 2,035,355 Weise Mar. 24, 1936 2,035,359 Anjeskey Mar. 24, 1936 2,334,940 LeTourneau Nov. 23, 1943 2,707,324 Walther May 3, 1955 2,900,015 Harrison Aug. 18, 1959 

